Overhead camshaft engine



y 1968 E. c. KIEKHAEFER ETAL 3,384,058

OVERHEAD CAMSHAFT ENGINE Filed April 21, 1967 2 Sheets-Sheet 1 FIG. I

/7 FIG. 2,

INVENTORS. ELMER CARL KIEKHAEFFR BCQQRL KIVUTII y 1968 E. c. KlEKHAEFE R ETAL 3,384,058

OVERHEAD CAMSHAFT ENG INE 2 Sheets-Sheet 2 Filed April 21, 1967 m. mm M mum s V50 5 e mKN L r M h cm W 5 m 6 a E: y k

United States Patent Oflice Patented May 21, 1958 3,384,058 OVERHEAD CAMSHAFT ENGINE Elmer Carl Kiekhaefer, Winter Haven, Fla, and Carl Knuth, Fond du Lac, Wis., assignors to Brunswick Corporation, Chicago, L, a corporation of Delaware Filed Apr. 21, 1967, Ser. No. 632,791 7 Claims. (Cl. 123-52) ABSTRACT OF THE DISCLOSURE A four-cycle internal combustion engine has its cylinders arranged in Siamese pairs with two separate crankshafts at opposite ends of the block, synchronized in operation either by a train of gears or a positive drive belt, and having overhead camshafts for actuating intake and exhaust valves in the heads of the corresponding cylinders. Each camshaft is driven directly from the adjacent crankshaft.

This invention relates to an overhead camshaft engine of the four-cycle internal combustion type.

The invention is applicable to engines having two cylinders and multiples of two cylinders.

The advantages of overhead camshaft actuation of the valves for four-cycle internal combustion engines have long been known. Nevertheless, practical engines employing such overhead camshafts have awaited developments in various types of drive connections between the crankshaft at one end of the cylinders and the camshaft at the other end.

The use of long belts and chains for driving overhead camshafts has presented problems in noise, in oiling and maintenance, in wear and stretching and thereby destroying the timing, and in overall life. Gears have been used but require substantial oiling which becomes a problem for the height needed.

The present invention proposes to arrange the cylinders in Siamese pairs wherein the head of one cylinder for each pair is adjacent the crank end of the opposite cylinder and vice versa. In this way there are two crankshafts and two camshafts for the engine, there being a crankshaft and a camshaft at each end of the cylinders. With this construction the drive connection is between the crankshaft of one cylinder and the camshaft of the adjacent cylinder and is short so that any one of the drive connections will be suitable Without encountering the problems previously referred to.

The invention further contemplates the positive synchronizing of the crankshafts by means of gears or a timing belt or other suitable means. Where it is desired to drive counter rotating propellers for marine purposes it is preferable to synchronize the crankshafts by gear means providing for counter rotation of the crankshafts. Where it is desired to provide a common output shaft driven from the two crankshafts the synchronizing is preferably accomplished by a timing belt which may be of the general type described and claimed in the copending application of Elmer Carl Kiekhaefer, Ser. No. 432,676, filed Feb. 15, 1965, now Patent No. 3,338,107 and assigned to a comm-on assignee with the present application.

The accompanying drawing illustrates the best mode presently contemplated by the inventors for carrying out the invention.

In the drawings:

FIGURE 1 is a schematic sectional view of an engine taken partially axially of a pair of Siamese arranged cylinders;

FIG. 2 is a schematic section taken generally on line 22 of FIG. 1;

FIG. 3 is a schematic section taken generally on line 33 of FIG. 1;

FIG. 4 is a detail schematic view of the synchronizing connection between the several shafts utilizing gearing; and

FIG. 5 is a similar view utilizing a timing belt.

The internal combustion engine illustrated has its cylinders arranged in Siamese pairs, only one pair of which is illustrated and comprises a cylinder block 1 having the spaced parallel cylinders 2 and 3 disposed with their corresponding heads 4 and 5 opposed in direction.

Pistons 6 and 7 operate in the corresponding cylinders 2 and 3 and are connected to individual crankshafts 8 and 9, respectively, by suitable connecting rods 10 and 11.

The cylinder heads 4 and 5 contain the necessary fuel inlet valves 12 and exhaust valves 13 for each cylinder. The valves 12 and 13 illustrated are of the poppet type with the valves held seated by suitable springs 14 disposed to bias the valve stems 15 outwardly.

Inward movement of each valve 12 and 13 for cylinder 2 is effected by earns 16 and 17, respectively, on a camshaft 18 extending across the closed end of the cylinder in a direction parallel to crankshafts 8 and 9.

Similarly, inward movement of each valve 12 and 13 for cylinder 3 is effected by earns 19 and 20, respectively. on a camshaft 21 extending across the closed end or the cylinder in a direction parallel to crankshafts 8 and 9.

Camshaft 18 for cylinder 2 is driven by a suitable connection such as the gears 22 and 23 from crankshaft S for cylinder 3. Likewise, camshaft 21 for cylinder 3 is driven by a suitable connection such as the gears 24 and 25 from crankshaft 8 for cylinder 2.

Gears 22 and 24 on the corresponding crankshafts S and 8 are one-half the pitch diameter of gears 23 an: 25 on the corresponding camshafts 18 and 21 to provide the necessary 2:1 speed reduction between the camshafts and the crankshafts of the engine.

Suitable end housings 26 and 27 enclose the opposite ends of block 1 and provide the necessary crank cases 21 and 29 and the closed water cooling passage 30 arount the cylinders.

It will be observed that by driving camshaft 18 of cylin der 2 directly from the adjacent crankshaft 9 of cylinder 3 a short drive connection is obtained which can be main tained accurate for a long period of time. The same i: true of the direct drive connection between camshaft 21 of cylinder 3 and the adjacent crankshaft 8 of cylinder 2 Synchronization of the two crankshafts 8 and 9 is pro vided by a suitable power connection between the same.

Where it is desired to provide a dual counter rotating shaft output the synchronizing means may comprise tht gear train illustrated in FIG. 4 and consisting of gears 31 $2, 33 and 34 in series mesh with gear 31 on shaft 8 am gear 34 on shaft 9. The counter rotating output shafts ma comprise either the crankshafts 8 and 9 or the shafts 3! and 36 upon which the corresponding gears 32 and 33 an secured. If it is desired to have a single output shaft it i. possible to utilize any one of the shafts 8, 9, or 36.

Freferably, where counter rotation of the crankshaft 8 and 9 is not required, the synchronizing means illus trated in FIG. 5 may be employed. It comprises a tlmll'll belt 37' having internal cogs 38 which interlock with 1 gear 39 on shaft 8 and a gear 40 on shaft 9. By providin; cogs 41 on the outer surface of belt 37 it may additional 1y interlock with a gear 42 on camshaft 18 and with gear 43 on camshaft 21 as the belt passes between th gears 39 and 43 at one end and between gears 40 and 41 at the other end.

Various modes of carrying out the invention are con templated as being within the scope of the following claim particularly pointing out and distinctly claiming the sub ject matter which is regarded as the invention.

We claim:

1. A four cycle internal combustion engine comprising a pair of synchronized crankshafts, at least one pair of cylinders disposed in opposite Siamese arrangement with the head of one cylinder adjacent the crankshaft of the other cylinder in each instance, inlet and exhaust valves in the head for each cylinder, an overhead camshaft for each cylinder With cams thereon for actuating the corresponding valves for the cylinder, and separate means driving each said camshaft from the adjacent crankshaft.

2. The engine of claim 1 in which each of said separate drive means comprises directly intermeshing gears on the adjacent camshaft and crankshaft.

3. The engine of claim 1 in which said crankshafts are synchronized by a gear train therebetween.

4. The engine of claim 3 in which said gear train comprises an even number of gears providing for counter rotation of said crankshafts.

5. The engine of claim 3 in which said gear train comprises an odd number of gears providing for unidirectional rotation of said crankshafts.

6. The engine of claim 1 and a timing belt connecting said crankshafts to synchronize the rotation thereof.

7. The engine of claim 6 in Which said timing belt comprises cogs on the inner surface thereof meshing with gears on the opposite crankshafts, and cogs on the outer surface of the belt meshing with gears on the opposite camshafts.

References Cited UNITED STATES PATENTS 1,198,334- 9/1916 Emerson 1235Z 1,911,991 5/1933 Cosby 123-52 1,971,176 8/1934 Dugelay 123-52 2,596,410 5/1952 Jordan 123-52 3,351,045 11/1967 Knuth 12352 WENDELL E. BURNS, Primary Examiner. 

